Tricritical point and phase diagram based on critical scaling in monoaxial chiral helimagnet Cr1/3NbS2

TL;DR

This study investigates the critical behavior and phase diagram of Cr$_{1/3}$NbS$_{2}$, revealing a tricritical point and critical points associated with chiral magnetic soliton lattice, using critical scaling and magnetization analysis.

Contribution

It provides the first detailed critical scaling analysis and phase diagram construction for Cr$_{1/3}$NbS$_{2}$, identifying tricritical and critical points in its magnetic phase transitions.

Findings

Critical exponents close to 3D Heisenberg model

Identification of a tricritical point at CSL, FFM, and PM states

Phase diagram with two critical points

Abstract

In this work, the magnetism of the single crystal Cr$_{1/3}$NbS$_{2}$, which exhibits chiral magnetic soliton lattice (CSL) state, is investigated. The magnetization displays strong magnetic anisotropy when the field is applied perpendicularly and parallel to the $c$-axis in low field region ($H<H_{S}$, $H_{S}$ is the saturation field). The critical exponents of Cr$_{1/3}$NbS$_{2}$ are obtained as $\beta=$ 0.370(4), $\gamma=$ 1.380(2), and $\delta=$ 4.853(6), which are close to the theoretical prediction of three-dimensional Heisenberg model. Based on the scaling equation and the critical exponents, the $H-T$ phase diagram in the vicinity of the phase transition is constructed, where two critical points are determined. One is a tricritical point which locates at the intersection between the CSL, forced ferromagnetic (FFM), and paramagnetic (PM) states. The other one is a critical point situated at the boundaries between CSL, helimagnetic (HM), and PM states.